In medical technology, systems based on nuclear spin resonance are used for image generation, like for example magnetic resonance systems (MR) or devices for the magnetic navigation (MN) of probes within the body. Systems of this type known for example from the previously mentioned DE 102 03 372 A1 require fields, some of a variable nature, with extremely high field intensities of up to 0.1 Tesla for MN systems and 3 Tesla for MR systems.
Strong magnetic fields can result in unwanted damage and disturbance to electronic devices, including medical devices as well as clocks and magnetic cards.
There are also known cases in which patients in an area of high field intensity for examination purposes are injured or killed by metal objects accelerating towards them. Personal injury can also result, when people with metal implants are located in the area of the magnetic fields. An injury to the myocardium can occur particularly in patients with pacemakers due to the pacemaker electrodes heating up as a result of induction or heart pacemakers can fail as a result of faults at the pulse generator.
To reduce this risk or prevent it completely, warning signs have hitherto been used in the access area of the systems mentioned based on nuclear spin resonance and the critical area of the field lines has been marked on the floor of the examination room using colored adhesive tape. Notification of this type is nevertheless frequently overlooked or unintentionally disregarded. Furthermore, medical personal also often forget to look out for implants, or incorrect information is given unwittingly on the part of the patient.
DE 196 26 596 C2 discloses a circuit for protecting a transportable electronic system from a magnetic field with high level, which is connected to the electronic system and comprises a measuring unit for field detection and several warning devices.